1. Field of the Invention
This invention relates to a process for the production of polyol compounds by condensation of glycerol in the presence of lithium compounds and, optionally, subsequent transesterification of the oligoglycerol mixtures obtained with fatty acid glyceride esters and to their use for the production of polymers.
2. Statement of Related Art
Polyurethanes are produced by reaction of diisocyanates with compounds containing at least two free hydroxyl groups. Polyol compounds used for the production of such plastics include, for example, ring opening products of epoxide compounds with alcohols [Fette, Seifen, Anstrichmitt., 89, 147 (1987)]. Oligoglycerol mixtures are also suitable in principle for this application. However, since the self-condensation of glycerol is normally carried out in the presence of strong bases, more particularly in the presence of sodium or potassium hydroxide, the resulting technical oligoglycerol mixtures generally have a high residual alkali content which can be extremely troublesome in the polyurethane reaction and could lead to unwanted shrinkage of the plastics obtained. The further reaction of the oligoglycerol mixtures with fats and oils to form so-called transesterification polyols or uralkyds, which are also suitable as raw materials for the production of polyurethanes, is also problematical for the same reason. Accordingly, it has hitherto been necessary to free oligoglycerol mixtures from salts with considerable effort before any further reaction.
The problem addressed by the present invention was to provide a new process for the production of polyols based on self-condensation products of glycerol which would be free from the disadvantages mentioned above.